1. Field of the Invention
The present invention relates to electrical cables and connectors. More specifically, the present invention relates to electrical interface extension cables with an automatic isolation function for switching between a primary input and a secondary input.
2. Description of the Related Art
User accessible interface connectors are prevalent in modern electrical and electronic devices. Such connections are provided on most audio and video devices, as well as computing devices, games, power devices, appliances, cameras, camcorders, and so forth. Electrical connections include terminals, plugs, jacks, and other types of electrical connections, which are typically coupled to, or used to couple with, an electrical cable or wire. There are a large number of promulgated standards that define both the physical and electrical connection standards, and there are perhaps a greater number of proprietary interface designs used by manufacturers of such devices. Some devices present plural connections that correspond to plural difference interface specifications.
One common manifestation of an electrical connection is the input terminal to a device or appliance. An input may be for coupling an external power source, an external signal source, or plural signal sources, an external data source, or other input source connection. For example, a television or video display terminal typically has a group of input connectors for coupling audio and video signals from an external source, such as a DVD player or video camcorder. A common purpose and feature of the user accessible electrical interface connector is the flexibility it provides in connecting and disconnecting one or more external sources from time to time. In some instances a user couples a signal source to an input connector on a device that stays connected permanently. An example is the connection from a DVD player to the input connectors on the back of a television set, which is typically connected once and remains so for an extended period of time. In other instances, an input source is connected and disconnected from time to time as a matter of user convenience. An example is the connection between a portable video camcorder and a television set. In this example, the user moves about recording video and audio content with the camcorder, and later couples the camcorder to the television when playback is desired. For playback, the devices are connected, and for recording, the devices are disconnected.
While the presence of user accessible electrical interface connectors is a convenience for users, it also defines connection and disconnection tasks that user must accomplish in order to connect devices together. In the case where a connection is made on a largely permanent basis, the task of making the connection is a minimal inconvenience. In the case where a device is connected and disconnected more frequently, the connection task becomes more substantial. In another situation, where two or more input sources are intermittently coupled to a single set of electrical connections, that task of connecting and disconnecting becomes an inconvenience. An example of this is where a user desires to couple both a DVD player and a video cassette player to a television set that has just a single set on input connectors. This situation forces the user to disconnect one input source and re-connect the other every time a change is made from one source to another. The inconvenience is exacerbated in the case where the television external input connectors are not conveniently located, such as being placed on the back of the television, which is set into a cabinet that does not offer access to the back of the set. A similar scenario can readily be envisioned for output connections to plural input connections as well.
The prior art has addressed the problem of dealing with inconveniently located electrical interface connectors. Several manufacturers make and sell extension cables that extend an input connector from an inconvenient location to a more convenient location. An example of this is the audio and video extension cable that is connected to the audio and video inputs on the back of a television set, and allows the user to route the cable to a convenient location, where a duplicate set on input terminals is presented for coupling external input sources. This solution, however, does not overcome the issue of switching between plural input sources to a single input terminal. Thus it can be understood that there is a need in the art for a apparatus and method of overcoming the problems associated with both inconveniently located electrical connections and user's need to connect more input sources that available input connectors provide for.